For analyzing a specific component contained in a sample, use may be made of an optical method. An example of such is one that utilizes a color reaction occurring in a test tool. In this kind of analysis, the degree of coloration occurring on the test tool may be checked with eyes. However, when the concentration of a specific component is analyzed quantitatively, an appropriate analyzing device is used.
Some analyzing devices are designed to begin automatic measurement for the amount of specific component after a test tool has been set in the device. Such an analyzing device, as shown in FIG. 17, includes a light source 992 for irradiating a reagent pad 991 of the test tool 990, and a light-receiving unit 993 for receiving the scattered light from the reagent pad 991, whereby analysis of the sample is performed on the basis of the quantity of light received by the light-receiving unit 993 (see JP-A-H09-145613, for example).
In the illustrated example, the test tool 990 is irradiated directly with the light from the light source 992, and the scattered light from the test tool 990 is received directly in the light-receiving unit 993. Hence, for the scattered light from the test tool 990 to be received, the light source 992 and the light-receiving unit 993 need be disposed such that the light reception axis S2 of the light-receiving unit 993 is inclined relative to the light emission axis S1 of the light source 992. Accordingly, the distance between the light source 992 and the light-receiving unit 993 tends to be large, thereby making it difficult to reduce the size of a light-measuring mechanism employing the above method, and hence the size of the analyzing device incorporating the light-measuring mechanism. Moreover, since scattered light is received, the quantity of light received in the light-receiving unit 993 is small. Unfavorably, this increases the likelihood of measurement errors.
Meanwhile, for an analyzing device to perform automatic quantity measurement, the analyzing device needs to recognize that a test tool has been supplied. Typically, such recognition of a test tool is automatically performed in the analyzing device, though it is also possible to arrange that the recognition is initiated by the user operating an operation switch on the device.
Typically, the automatic recognition (detection) of the test tool in the analyzing device is attained through a light sensor. An example of such a light sensor, shown in FIG. 18, uses scattered light from a test tool 994. In the illustrated example, the light source 995 emits light toward a target site in which the test tool 994 is to be placed. When scattered light from the target site is received by the light-receiving unit 996, it is determined that the test tool 994 is placed in the target site.
However, with the above detection method, reflection light is received in the light-receiving unit 996 not only when the test tool 994 is placed in the target site, but also when the user's hand passes over the target site or the test tool 994 is brought above the target site. In such cases, the analyzing device may erroneously recognize that the test tool 994 has been properly set in the target site, and begin an analysis operation.